Wall Street rallied sharply on Monday, juiced by a jump in Apple shares and gains from energy stocks that were backed by stronger oil prices.

Shares in Apple, which had lost about one-fifth of their value in the past month on worries about the company’s slowing sales growth, finished 3.7 percent higher after Warren Buffett’s Berkshire Hathaway reported taking a stake of about $1 billion in the iPhone maker.

Oil prices hit six-month highs on Monday on global supply outages and long-time bear Goldman Sachs taking a more positive view on the market, although a stockpile build at the U.S. storage hub for crude futures limited gains.

Brent crude futures traded flat at $48.96 per barrel in early Asia, after having risen 2.4 percent on Monday, when it rallied to $49.47 earlier, its highest since early November, in a test towards $50.

Yet concerns about a slowdown in the Chinese economy could weigh on Asian shares after investment, factory output and retail sales all grew more slowly than expected in April, in data published on Saturday.

In the past month, shares in Greater China are among the worst performers globally, with Hong Kong, Taiwan and Shanghai shares all registering fall of around 7 percent.

In the currency market, the British pound rose 0.3 percent in early Asian trade to $1.4445 helped in part by the report that the “remain” camp held a 15-point lead over its “leave” rivals in Britain’s EU referendum campaign.

The dollar was little changed against other currencies. Against the yen, the U.S. currency stood at 109.09 yen, stuck in its well-worn range in the past week.

The euro traded at $1.1315, off its two-week low of $1.1283 touched on Friday.